UNA LECTURA REPUBLICANA I FEDERAL DE L'AUTODETERMINACIÓ

The prospect of offering a positive solution to the right to self-determinationand to regulate it constitutionally is an inevitable step in the convergence betweenthe liberal democratic tradition and republican patriotism. As societiesbecome increasingly democratic, and become more advanced in terms ofmaterial equality, the more national diversity is recognised and the closer wecome to a republican and federal culture, given that we are allowing real nationsto speak without internal or external discrimination or domination. Arepublican and federal interpretation of self-determination is necessary tosucceed in reversing the treatment of national conflicts within liberal democracies.The time for unilateral decisions based on sovereignty is over, insofaras democratic constitutions include and regulate the multi-nation state andthe federal principle, such as recognition and the means to agreement betweennations based on equality, respectively

Federalismo plurinacional y pluralismo de valores

Ferran Requejo. Madrid, Centro de Estudios Políticos y Constitucionales. 200

La reforma dels estatuts i la llengua catalana

L'Estat espanyol té l'obligació i la responsabilitat pública de promoure totes les llengües oficials, d'estendre'n el coneixement. Una concepció federal de l'Estat en matèria de llengua neix del principi d'igualtat entre les llengües oficials. Seria un pas de gran relleu el reconeixement de l'oficialitat estatal per al català, el gallec i el basc, així com el deure de conèixer-les en les comunitats autònomes respectives. No és encara una solució prou federal, però sí que és indubtablement un gir que tindria conseqüències, per exemple, en la mateixa Unió Europea, en el reconeixement i l'oficialitat de les llengües nacionals sense estat propi. La conclusió que es pot treure de la reforma dels estatuts de Catalunya, de les Illes Balears i de la Comunitat Valenciana en matèria de llengua és que s'ha de reconèixer un avanç, però és insuficient. S'han de valorar positivament els importants canvis introduïts en el nou Estatut d'autonomia de Catalunya, també els avanços menors en els casos de les Illes Balears i de la Comunitat Valenciana. Alhora, cal avisar sobre possibles instrumentalitzacions polítiques de la llengua, especialment en el cas de la Comunitat Valenciana, en utilitzar-la com a frontera política i eina útil per a opcions partidistes i de confrontació. També cal assenyalar la necessitat d'avançar cap a una fonamentació comunitària i no únicament territorial de la llengua pròpia, compatible amb la seva promoció com a llengua comuna i preferent en els territoris plurilingües. La normalització del català no serà assolida mentre no es compleixin les condicions següents: 1) ésser un deure el seu coneixement; 2) ésser la llengua comuna, vehicular i preferent en l'aprenentatge i en l'ensenyament, i la llengua d'ús preferent en els mitjans de comunicació públics i privats; 3) ésser la llengua preferent d'ús social per part de la ciutadania i les seves relacions en el món econòmic, social, cultural i institucional

How can we improve energy efficiency through user-directed vectorization and task-based parallelization?

Heterogeneity, parallelization and vectorization are key techniques to improve the performance and energy efficiency of modern computing systems. However, programming and maintaining code for these architectures poses a huge challenge due to the ever-increasing architecture complexity. Task-based environments hide most of this complexity, improving scalability and usage of the available resources. In these environments, while there has been a lot of effort to ease parallelization and improve the usage of heterogeneous resources, vectorization has been considered a secondary objective. Furthermore, there has been a swift and unstoppable burst of vector architectures at all market segments, from embedded to HPC. Vectorization can no longer be ignored, but manual vectorization is tedious, error-prone, and not practical for the average programmer. This work evaluates the feasibility of user-directed vectorization in task-based applications. Our evaluation is based on the OmpSs programming model, extended to support user-directed vectorization for different SIMD architectures (i.e. SSE, AVX2, AVX512, etc). Results show that user-directed codes achieve manually-optimized code performance and energy efficiency with minimal code modifications, favoring portability across different SIMD architectures

Stencil codes on a vector length agnostic architecture

Data-level parallelism is frequently ignored or underutilized. Achieved through vector/SIMD capabilities, it can provide substantial performance improvements on top of widely used techniques such as thread-level parallelism. However, manual vectorization is a tedious and costly process that needs to be repeated for each specific instruction set or register size. In addition, automatic compiler vectorization is susceptible to code complexity, and usually limited due to data and control dependencies. To address some these issues, Arm recently released a new vector ISA, the Scalable Vector Extension (SVE), which is Vector-Length Agnostic (VLA). VLA enables the generation of binary files that run regardless of the physical vector register length. In this paper we leverage the main characteristics of SVE to implement and optimize stencil computations, ubiquitous in scientific computing. We show that SVE enables easy deployment of textbook optimizations like loop unrolling, loop fusion, load trading or data reuse. Our detailed simulations using vector lengths ranging from 128 to 2,048 bits show that these optimizations can lead to performance improvements over straight-forward vectorized code of up to 56.6% for 2,048 bit vectors. In addition, we show that certain optimizations can hurt performance due to a reduction in arithmetic intensity, and provide insight useful for compiler optimizers.This work has been partially supported by the European HiPEAC Network of Excellence, by the Spanish Ministry of Economy and Competitiveness (contract TIN2015-65316-P), and by the Generalitat de Catalunya (contracts 2017-SGR-1328 and 2017-SGR-1414). The Mont-Blanc project receives funding from the EUs H2020 Framework Programme (H2020/2014-2020) under grant agreements no. 671697 and no. 779877. M. Moreto has been partially supported by the Spanish Ministry of Economy, Industry and Competitiveness under Ramon y Cajal fellowship number RYC-2016-21104. Finally, A. Armejach has been partially supported by the Spanish Ministry of Economy, Industry and Competitiveness under Juan de la Cierva postdoctoral fellowship number FJCI-2015-24753.Peer ReviewedPostprint (author's final draft